While homosexuality has of course been around as long as humans have, medical and academic studies of homosexuality have been a relatively recent phenomenon.

Medical literature on LGBT individuals expanded in in the late 19th century as medical and legal experts were tasked with determining whether people accused of criminal sexual behavior should be considered innocent because of a physical or psychological defect.

Notable physicians and researchers in the late 19th and early 20th centuries included Magnus Hirschfield (1868-1935) and Sandor Rado (1890-1972). Magnus Hirschfeld was a German sexologist who argued homosexuality was a natural, biological variant in the spectrum between full maleness and femaleness. Hirschfeld was also openly gay and an advocate for homosexual rights. Analyst Sandor Rado considered homosexuality a phobic avoidance of the other sex that is caused by parental prohibitions against childhood sexuality.

Alfred Kinsey’s research studies on homosexuality in the 1940s and 1950s were incredibly influential and marked a cultural shift away from the notion that homosexuality was a pathology and toward the idea that it is a normal variant of human sexuality. Kinsey introduced a 0 to 6 scale to classify sexual behavior or fantasy from “exclusively heterosexual” to “exclusively homosexual”; this is called the Kinsey Scale. The Kinsey Reports, two books on human sexual behavior written by Kinsey and several others, found that 37% of males and 13% of females had at least some homosexual experience and 10% of males were essentially exclusively homosexual.

Despite progress on LGBT issues in the 20th century, it wasn’t until 1973 that the American Psychiatric Association removed homosexuality from its list of mental disorders. Around the same time, as there was increasing interest in gay and lesbian rights, queer studies and gender studies began to grow. There are currently at least five academic institutions in the U.S. with undergraduate programs in queer studies. In 2005, the first doctoral program for gender studies was approved.